Electrical circuit for thermionic discharge devices



Jan. 1 1,523,898

E. REISZ ELECTRICAL CIRCUIT FOR THERMIONIC DISCHARG'EDEVICES Filed May 25, 1921 atented.Jan. -20, 1925.

UNITED sTA ss "1,523 PATENT osric;

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Application filedlriay 25, 1921. Serial No." 472,618.

filed applications in Germany April 8, 1919,

and Oct. 2-5, 1919), of which the following is a full, clear, and exact description.

This invention relates to electrical circuits for use in connection with thermionic discharge devices, and has for an object'the provision of a circuit arrangement whereby the degree of amplification of these devices is increased.-

Another object resides in the provision of means whereby the use of inductive windings in-a circuit for the transmission of primary energy to the amplifiers and the resonance caused by. the capacity and self-induction of the inductive winding can be avoided. V

A further object resides in the provision of means whereby sound vibrationscan be directly transmitted to the input circuit of an amplifier system whereby corresponding oscillations-therein are produced in a new and improved manner.

ALSblll further object resides in the provision of means whereby the sensibility of the mechanism for transmitting sound waves to the input circuit of the amplifier can begreatly increased.

of means whereby transmittingcircuits for average frequencies can be made without it being necessary to have special apparatus for dperating the same. i

. A further object resides in the provision of means whereby the tuning of the cir-- cuits can be made inv a very exact manner, while the electrical characteristics of the thermionic discharge devices do notinfluence the tuning.

The invention is illustrated in in s, of which igure 1 represents a circuit in which sound waves are transmitted to the. input circuit of the amplifier;

Figure 2 represents the condenser used; and i Figure 3 represents a transmitting cirthe' drawcuit involving the use of a plurality of adapted to increase the amplifying power the vibration of the membrane 14. .The I amplifiers.

These new circuit arrangements .are

ofthermionic discharge devices with direct electron current Without it being'necessary to alter the form, location or normal characteristics of the electrodes. possible by the invention, since the vibrations in the input circuit are caused by a condenser the capacity of which may be changed by the primar r energy applied to I I the input circuit.

For instance, one of the plates of the condenser may be movably adjusted so that it is moved by the vibrations of the primary energy. I

In Figure 1 is shown a working example of the new circuit arrangement schematically. in this arrangement 1' is an amphfier with three electrodes, the cathode 2, the grid 3 and the anode 4; and 5, 6 and 7 respectively-are the corresponding working batteries; Battery 6 is required to place a normal potential on the grid 3. The input circuit also contains a non-inductive resist-- ance 8, and a condenser 9. The condenser 9 comprises a movable condenser transmitting plate 13 and a stationary plate 17. Y The movable plate'13- is carried by a membrane 14. 2

. The distance between the stationary and r movable plates of the condenser 9 can also be regulated according to the strength of the primary energy. Y

When this circuit arrangement is to be used for sei'iding conversations or sound 7 vibrations which may be recorded on a roll Another object resides in the provision,

which speech is recorded in. the ordinary way. The needle 15 rests on this record and when the record is turned transmits its movement to the membrane 14, shown 105 particularly in Figure 2. The side of the membrane l l adjacent the stationary plate 17 of the condenser-is provided with a thin metal sheet 13, as above mentioned, so that these two metal plates form a condenser, the

capacity of which is changed according to This is made in the condenser cause changes in the input circuit of the tube and influence the potential of the grid 24 whereby the out at circuit-of the tube is influenced in t e well known manner and influences a receiver 25 connected to the anode of the second ampli- 28 is placed to the en fier 26.

To increase the sound vibrations, a second amplifier 26 can be used in such a circuit as is represented in Figure 3. In the anode circuit of the first am lifier 27 a resistance of which the input circuit of the second amplifier 26, including caused by'the output current of vibrations of the first amplifier on the resistance 28 are transmitted therethrofigh to. the input circuit of the second amp er and produce the desired vibrations in the output circuit of the second tube. I

The gradual increase of amplification by the use of a plurality of tubes tapped across resistances in the circuit of previous tubes is known in the art. However, their use in connection with a condenser such as shown in this application is new, as hereby itzhas been made possible to amplify sound waves in the desired manner with current amplifiers without, the use of transmission coils or spools. With such recorders of sound waves as are now in use by means of a microphone it is necessary to have for each amplifying circuit at least one induction or transmission winding or s 1. These windin cause in their amplig g circuit by their self-induction and capacity a resonance which is very often disturbing in the receiver. The arrangements as described, to transform the recorded words into an electrical current, has also the advantage that the arrangement now in use to adjust the vibrating membrane can be preserved and that the movements of the membrane caused by the turning of the record or the roll do not produce any sound, which is always the case with microphones filled with carbon particles.-

It is apparent that modifications can be made in the circuit arran ments and in the apparatus. used therewith without departing from the spirit of the invention: a condenser 29, is connected. The changes What I claim is:

In an apparatus of the character described, a combined diaphragm and condenser plate, a second condenser plate arranged in operative relation to the diaphragm, an amplifying electron tube having a source of electromotive force between its anodeand cathode and a source of electro-' motive force for its cathode, and connections whereby the diaphragm and second condenser late may be subjected to the combined e ectromotive force between the anode and cathode and electromotive force for said cathode.-

- EUGEN REISZ. 

